The tiny southern African kingdom of Lesotho has been hit with a 50% reciprocal trade tariff by US President Donald Trump, the highest levy of any single state on his long list of target economies.

Lesotho, which Trump had ridiculed in March as a country "nobody has ever heard of", is a poor and landlocked country with a gross domestic product of just over $2-billion.

It has a large trade surplus with the United States, mostly made up of diamonds and textiles, including Levi's jeans.

Its exports to the United States, which in 2024 totalled $237-million, account for more than 10% of GDP, Oxford Economics said.

Trump on Wednesday imposed sweeping new reciprocal tariffs on global trading partners, upending decades of rules-based trade and threatening cost increases for consumers.

Trump said the "reciprocal" tariffs were a response to duties and other non-tariff barriers put on US goods. Lesotho charges 99% tariffs on American goods, according to the US administration.

In Africa, the move signalled the end of the AGOA (African Growth and Opportunity Act) trade deal that was supposed to help African economies develop through preferential access to US markets, trade experts said.

It also compounded the pain after Trump's administration dismantled USAID, the government agency that was a major supplier of aid to the continent.

The government of Lesotho, a mountainous nation of about 2-million people that is encircled by South Africa, had no immediate comment on the trade tariffs on Thursday.

But its foreign minister told Reuters last month the country, which has one of the highest HIV/AIDS infection rates in the world, was feeling the impact of the aid cuts as the health sector had been reliant on them.

The formula used to calculate the US tariffs took the US trade deficit in goods with each country as a proxy for alleged unfair practices, then divided it by the amount of goods imported into the United States from that country.

The resulting tariff equals half the ratio between the two, meaning countries such as Lesotho and Madagascar, which import only small quantities of US goods, have been hit with more punitive tariffs than much richer countries.